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Commit 8fe23e05 authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds
Browse files

mm: clear node in N_HIGH_MEMORY and stop kswapd when all memory is offlined 



When memory is hot-removed, its node must be cleared in N_HIGH_MEMORY if
there are no present pages left.

In such a situation, kswapd must also be stopped since it has nothing left
to do.

Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarLee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Rik van Riel <riel@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9b5e5d0f

include/linux/swap.h

+1 −0
Original line number Diff line number Diff line
@@ -273,6 +273,7 @@ extern int scan_unevictable_register_node(struct node *node); 
extern void scan_unevictable_unregister_node(struct node *node);



extern int kswapd_run(int nid);

extern void kswapd_stop(int nid);



#ifdef CONFIG_MMU

/* linux/mm/shmem.c */

mm/memory_hotplug.c

+4 −0
Original line number Diff line number Diff line
@@ -853,6 +853,10 @@ int offline_pages(unsigned long start_pfn, 


	setup_per_zone_wmarks();

	calculate_zone_inactive_ratio(zone);

	if (!node_present_pages(node)) {

		node_clear_state(node, N_HIGH_MEMORY);

		kswapd_stop(node);

	}



	vm_total_pages = nr_free_pagecache_pages();

	writeback_set_ratelimit();

mm/vmscan.c

+22 −6
Original line number Diff line number Diff line
@@ -2173,6 +2173,7 @@ static int kswapd(void *p) 
	order = 0;

	for ( ; ; ) {

		unsigned long new_order;

		int ret;



		prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);

		new_order = pgdat->kswapd_max_order;
@@ -2184,20 +2185,24 @@ static int kswapd(void *p) 
			 */

			order = new_order;

		} else {

			if (!freezing(current))

			if (!freezing(current) && !kthread_should_stop())

				schedule();



			order = pgdat->kswapd_max_order;

		}

		finish_wait(&pgdat->kswapd_wait, &wait);



		if (!try_to_freeze()) {

			/* We can speed up thawing tasks if we don't call

			 * balance_pgdat after returning from the refrigerator

		ret = try_to_freeze();

		if (kthread_should_stop())

			break;



		/*

		 * We can speed up thawing tasks if we don't call balance_pgdat

		 * after returning from the refrigerator

		 */

		if (!ret)

			balance_pgdat(pgdat, order);

	}

	}

	return 0;

}
@@ -2451,6 +2456,17 @@ int kswapd_run(int nid) 
	return ret;

}



/*

 * Called by memory hotplug when all memory in a node is offlined.

 */

void kswapd_stop(int nid)

{

	struct task_struct *kswapd = NODE_DATA(nid)->kswapd;



	if (kswapd)

		kthread_stop(kswapd);

}



static int __init kswapd_init(void)

{

	int nid;